Lanzilotto Valeria, Grazioli Cesare, Stredansky Matus, Zhang Teng, Schio Luca, Goldoni Andrea, Floreano Luca, Motta Alessandro, Cossaro Albano, Puglia Carla
Department of Physics and Astronomy, Uppsala University P.O. Box 516 751 20 Uppsala Sweden
Department of Chemistry, Sapienza University of Rome P.le Aldo Moro 8 00185 Roma Italy.
Nanoscale Adv. 2021 Feb 23;3(8):2359-2365. doi: 10.1039/d0na01034k. eCollection 2021 Apr 20.
The water-splitting photo-catalysis by carbon nitride heterocycles has been the subject of recent theoretical investigations, revealing a proton-coupled electron transfer (PCET) reaction from the H-bonded water molecule to the CN-heterocycle. In this context, a detailed characterization of the water-catalyst binding configuration becomes mandatory in order to validate and possibly improve the theoretical modeling. To this aim, we built a well-defined surface-supported water/catalyst interface by adsorbing water under ultra-high vacuum (UHV) conditions on a monolayer of melamine grown on the Cu(111) surface. By combining X-ray photoemission (XPS) and absorption (NEXAFS) spectroscopy we observed that melamine adsorbed onto copper is strongly tilted off the surface, with one amino group dangling to the vacuum side. The binding energy (BE) of the corresponding N 1s component is significantly higher compared to other N 1s contributions and displays a clear shift to lower BE as water is adsorbed. This finding along with density functional theory (DFT) results reveals that two adjacent melamine molecules concurrently work for stabilizing the H-bonded water-catalyst complex: one melamine acting as a H-donor the amino-N (NH⋯OHH) and another one as a H-acceptor the triazine-N (C[double bond, length as m-dash]N⋯HOH).
氮化碳杂环的光催化水分解一直是近期理论研究的主题，研究揭示了质子耦合电子转移（PCET）反应，即从氢键合的水分子转移至CN杂环。在此背景下，为了验证并可能改进理论模型，对水 - 催化剂结合构型进行详细表征变得至关重要。为此，我们通过在超高真空（UHV）条件下将水吸附在生长于Cu(111)表面的三聚氰胺单层上，构建了一个定义明确的表面支撑水/催化剂界面。通过结合X射线光电子能谱（XPS）和吸收光谱（NEXAFS），我们观察到吸附在铜上的三聚氰胺强烈地倾斜于表面，有一个氨基悬垂于真空侧。与其他N 1s贡献相比，相应N 1s组分的结合能（BE）显著更高，并且随着水的吸附，BE明显向更低值移动。这一发现以及密度泛函理论（DFT）结果表明，两个相邻的三聚氰胺分子同时作用于稳定氢键合的水 - 催化剂复合物：一个三聚氰胺作为氢供体——氨基 - N（NH⋯OHH），另一个作为氢受体——三嗪 - N（C[双键，长度为m破折号]N⋯HOH）。
Zotero 插件
